首页 / 软件开发 / Delphi / Delphi 2009泛型容器单元（Generics.Collections）[4]: TDictionary<T>

Delphi 2009泛型容器单元（Generics.Collections）[4]: TDictionary<T>2012-02-22 cnblogs 万一TDictionary 类似哈希表.

本例效果图:

代码文件:unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;
type
TForm1 = class（TForm）
Memo1: TMemo;
Edit1: TEdit;
Edit2: TEdit;
Button1: TButton;
Button2: TButton;
Button3: TButton;
Button4: TButton;
procedure FormCreate（Sender: TObject）;
procedure FormDestroy（Sender: TObject）;
procedure Button1Click（Sender: TObject）;
procedure Button2Click（Sender: TObject）;
procedure Button3Click（Sender: TObject）;
procedure Button4Click（Sender: TObject）;
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses Generics.Collections; {Delphi 2009 新增的泛型容器单元}
var
Dictionary: TDictionary<Cardinal,string>;
{定义一个泛型 TDictionary 类, 指定有 Cardinal、string 构成}
{建立}
procedure TForm1.FormCreate（Sender: TObject）;
begin
Dictionary := TDictionary<Cardinal,string>.Create;
Memo1.Clear;
Button1.Caption := Button1.Caption + " 添加";
Button2.Caption := Button2.Caption + " 删除";
Button3.Caption := Button3.Caption + " 尝试取值";
Button4.Caption := Button4.Caption + " 清空";
Edit1.Clear;
Edit2.Clear;
Edit1.NumbersOnly := True;
end;
{释放}
procedure TForm1.FormDestroy（Sender: TObject）;
begin
Dictionary.Free;
end;
{添加}
procedure TForm1.Button1Click（Sender: TObject）;
var
key: Cardinal;
value: string;
str: string;
k,v: Boolean;
begin
key := StrToIntDef（Edit1.Text, 0）;
value := Edit2.Text;
if value = "" then value := "Null";
k := Dictionary.ContainsKey（key）; {Key 是否存在}
v := Dictionary.ContainsValue（value）; {Value 是否存在}

if not k then
begin
Dictionary.Add（key, value）;
Memo1.Lines.Add（Format（"%d=%s", [key, value]））; {同步显示}
end;
if k and not v then
begin
str := Format（"key 已存在: %d=%s; 是否修改其值？", [key, Dictionary[key]]）;
if MessageBox（0, PChar（str）, "提示", MB_OKCANCEL or MB_ICONQUESTION） = mrOk then
begin
//Dictionary[key] := value; {Dictionary[key] = Dictionary.Item[key]}
Dictionary.AddOrSetValue（key, value）; {也可使用上一句}
Memo1.Lines.Values[IntToStr（key）] := value; {同步显示}
end;
end;
if k and v then
begin
str := Format（"%d=%s 已存在, 不能重复添加", [key, value]）;
MessageBox（0, PChar（str）, "错误", MB_OK + MB_ICONHAND）;
end;
Text := IntToStr（Dictionary.Count）;
end;
{删除: Remove}
procedure TForm1.Button2Click（Sender: TObject）;
var
key: Integer;
i: Integer;
begin
key := StrToIntDef（Edit1.Text, 0）;
if not Dictionary.ContainsKey（key） then
begin
ShowMessageFmt（"key: %d 不存在", [key]）;
Exit;
end;

Dictionary.Remove（key）;
Text := IntToStr（Dictionary.Count）;

{同步显示}
i := Memo1.Lines.IndexOfName（IntToStr（key））;
if i > -1 then Memo1.Lines.Delete（i）;
end;
{尝试取值: TryGetValue}
procedure TForm1.Button3Click（Sender: TObject）;
var
key: Integer;
value: string;
begin
key := StrToIntDef（Edit1.Text, 0）;
if Dictionary.TryGetValue（key, value） then
ShowMessageFmt（"key: %d 已存在, 其值是: %s", [key, value]）
else
ShowMessageFmt（"key: %d 不存在", [key]）
end;
{清空: Clear}
procedure TForm1.Button4Click（Sender: TObject）;
begin
Dictionary.Clear;
Text := IntToStr（Dictionary.Count）;
Memo1.Clear; {同步显示}
end;
end.